Many thyroid cancer cases linked to Chernobyl
Date: 24-Oct-01
Country: PORTUGAL
Although it is 15 years since a cloud of radioactive dust spewed from the explosion of Chernobyl's number four reactor in 1986, new cases of cancer associated with the accident are still being reported.
"Four years after the accident, an excess of thyroid cancers was noted among children who had been exposed to fallout from the disaster," said Professor Dillwyn Williams of the Strangeways Research Laboratory at England's Cambridge University.
"That increase has continued and new cases are still being seen in those who were children at the time of the accident."
Williams told the ECCO 11 cancer conference in Lisbon that children are particularly sensitive to the cancer after exposure to radiation - the only established cause of thyroid cancer.
"Exposure to isotopes of iodine gives the thyroid over 1,000 times the average dose to the rest of the body. The particular sensitivity of children to thyroid cancer after radiation exposure can be linked to a combination of a higher thyroid dose and the biology of thyroid growth - which falls to a very low level in adult life," he said.
The radioactive cloud that erupted from the explosion in Ukraine contained inert xenon gas and caesium but the largest components were radioactive isotopes of iodine, according to Williams.
The thyroid is a gland at the base of the throat that absorbs iodine from the diet and produces hormones to keep the body running properly. Thyroid cancer is rare.
Dr Elaine Ron of the U.S. National Cancer Institute in Bethesda, Maryland, said the risk of developing thyroid cancer could be highest 15 to 19 years after exposure.
If the theory is correct, many people who were children at the time of the explosion may still develop the illness.
Other research presented at the five-day meeting showed that the accident may also be linked to lung cancer.
Victor Chizhikov of the Cancer Research Centre in Moscow said 43 clean-up workers, both smokers and non-smokers, who had radioactive dust in their lungs after the accident had higher rates of lung cancer than a similar number of people who had not been exposed to the radioactive cloud.
About 8,000 doctors, scientists and nurses are attending the five-day cancer conference that began on Sunday.